1. Field of the Invention
The present invention relates generally to hay harvesting machinery and more particularly, to an apparatus for conditioning hay after it has been severed as a crop. The invention especially concerns a roll cover for use on rollers in a hay conditioner.
2. Description of the Related Art
Hay harvesting machines, also referred to as mower-conditioners, windrowers, dismower-conditioners, or hay swathers, use a crop harvesting header to sever the hay crop from the ground and convey it rearwardly to a conditioning mechanism. The conditioning mechanism operates to crush or crimp the severed crop at spaced apart intervals along the stem of the crop to facilitate the drainage of liquids from the crop. The dried crop may then be baled and removed from the field.
The conditioning mechanism typically employs a pair of counter-rotating, intermeshing rollers with some form of a lobed surface. The lobed surface of each roller typically comprises radially extended lugs or lobes, separated by grooves. The lobed surface of each roller meshes with a mating surface of the opposite counter-rotating roller.
The radial lug of the lobed surface may rotate about the roller axis as a continuous spiral for the entire length of the roller. Alternatively, the lobed surface of each roller may comprise a series of discontinuous lugs to form a pattern such as a helix with a defined lead, or a chevron or herringbone type pattern. Additionally, the conditioning roll surface may comprise a series of intermeshing raised geometric patterns.
The purpose of the conditioning rolls is to crush or break open the waxy stems of the plant crop material to promote rapid drying of the crop material for packaging and transport. The process of conditioning the crop material between the counter-rotating conditioning rolls creates abrasive wear to the surface of the conditioning rolls due to frictional and impinging forces upon the roll surfaces. The frictional and impinging wear of the conditioning roll surface is often dependent on such factors as the amount of material fed into the rollers, the amount of dusty or silty residues on the crop, the length of the crop stems, the rotation speed of the conditioning rolls, and the presence of foreign materials in the crop material.
Current elastomer covered conditioning rolls wear and polish quickly, creating worn areas or regions on the roll cover surfaces that reduce the conditioning action intended to be carried out by the lugs. The abrasion resistance can be increased by using higher cost elastomers, such as the urethane group of elastomers. However, the cost increase of the material is disproportionately high in relation to the increase in operational life of the conditioning roll cover. Metal conditioning rolls have also been used in high abrasion wear conditions, but the metal rolls are higher in cost and cause a loss in conditioning performance due to crop slippage through the rolls.